Add language for .remarkrc, .remarkignore to VSC

By default, VS Code can’t know the language associated with certain files
without extensions.
This addition tells VS Code, when this extension is installed, what language
are associated with `.remarkrc` and `.remarkignore`.

Closes GH-78.

Reviewed-by: Christian Murphy <christian.murphy.42@gmail.com>
Reviewed-by: Titus Wormer <tituswormer@gmail.com>

package.json

@@ -216,7 +216,21 @@
           }
         }
       }
-    }
+    },
+    "languages": [
+      {
+        "id": "ignore",
+        "extensions": [
+          ".remarkignore"
+        ]
+      },
+      {
+        "id": "json",
+        "filenames": [
+          ".remarkrc"
+        ]
+      }
+    ]
   },
   "devDependencies": {
     "@istanbuljs/nyc-config-typescript": "^1.0.1",